Reinforced concrete piles are known for use in the foundations of roadway bridges and the like. The piles are sunk deep into the ground and can for example provide a link between the bridge supports and the underlying rocks. The pile comprises a metallic pile cage embedded in concrete, the pile cage acting both as a reinforcement for the concrete and also as a means to tie the bridge support or the like to the pile. The pile cage comprises a number of cage bars which in use are arranged to lie substantially along the longitudinal axis of the pile. These bars are interconnected by one or more frames which maintain the separation and alignment of the cage bars, and in many designs of pile cage the frame comprises a helical wire which surrounds and interconnects the cage bars.
Often the cage is assembled off-site at a dedicated manufacturing plant, and is delivered to the site for insertion into the hole created for the pile.
If the depth of the pile is greater than the length of the available pile cages, then the piling contractor will have to splice together two or more pile cages, i.e. connect the top end of a lower pile cage to the bottom end of an upper pile cage.
The pile cage is lowered into a hole which has been drilled into the ground by a drill or augur. The pile cage can be pressed down into wet concrete, the concrete being pumped into the hole as the augur is removed therefrom. Alternatively, a casing is inserted into the hole and the pile cage is inserted into the casing, the concrete then being poured around the pile cage and the casing subsequently being removed (so that it can be reused). A casing will typically be used when the pile cages are required to be spliced.
When two pile cages are to be spliced together, the helical wire of one or both of the pile cages will typically be terminated away from the end of the cage bars, so that the cage bars project beyond the helical wire and allow an overlap to be created between the cage bars of the respective pile cages, the length of overlap required being determined in advance by the piling contractor.